J/A+A/667/A59 LP 890-9 (TOI-4306) light curves and RVs (Delrez+, 2022)
Two temperate super-Earths transiting a nearby late-type M dwarf.
Delrez L., Murray C.A., Pozuelos F.J., Narita N., Ducrot E., Timmermans M.,
Watanabe N., Burgasser A.J., Hirano T., Rackham B.V., Stassun K.G.,
Van Grootel V., Aganze C., Cointepas M., Howell S., Kaltenegger L.,
Niraula P., Sebastian D., Almenara J.M., Barkaoui K., Baycroft T.A.,
Bonfils X., Bouchy F., Burdanov A., Caldwell D.A., Charbonneau D.,
Ciardi D.R., Collins K.A., Daylan T., Demory B.-O., de Wit J.,
Dransfield G., Fajardo-Acosta S.B., Fausnaugh M., Fukui A., Furlan E.,
Garcia L.J., Gnilka C.L., Gomez Maqueo Chew Y., Gomez-Munoz M.A.,
Guenther M.N., Harakawa H., Heng K., Hooton M.J., Hori Y., Ikoma M.,
Jehin E., Jenkins J.M., Kagetani T., Kawauchi K., Kimura T., Kodama T.,
Kotani T., Krishnamurthy V., Kudo T., Kunovac V., Kusakabe N., Latham D.W.,
Littlefield C., McCormac J., Melis C., Mori M., Murgas F., Palle E.,
Pedersen P.P., Queloz D., Ricker G., Sabin L., Schanche N.,
Schroffenegger U., Seager S., Shiao B., Sohy S., Standing M.R., Tamura M.,
Theissen C.A., Thompson S.J., Triaud A.H.M.J., Vanderspek R., Vievard S.,
Wells R.D., Winn J.N., Zou Y., Zuniga-Fernandez S., Gillon M.
<Astron. Astrophys. 667, A59 (2022)>
=2022A&A...667A..59D 2022A&A...667A..59D (SIMBAD/NED BibCode)
ADC_Keywords: Stars, double and multiple ; Exoplanets ; Photometry ; Optical ;
Radial velocities
Keywords: planets and satellites: detection - stars: individual: LP 890-9 -
stars: individual: TIC 44898913 - stars: individual: TOI-4306 -
stars: individual: SPECULOOS-2 - techniques: photometric
Abstract:
In the age of JWST, temperate terrestrial exoplanets transiting nearby
late-type M dwarfs provide unique opportunities for characterising
their atmospheres, as well as searching for biosignature gases. In
this context, the benchmark TRAPPIST-1 planetary system has garnered
the interest of a broad scientific community.
We report here the discovery and validation of two temperate
super-Earths transiting LP 890-9 (TOI-4306, SPECULOOS-2), a relatively
low-activity nearby (32 pc) M6V star. The inner planet, LP 890-9 b,
was first detected by TESS (and identified as TOI-4306.01) based on
four sectors of data. Intensive photometric monitoring of the system
with the SPECULOOS Southern Observatory then led to the discovery of a
second outer transiting planet, LP 890-9 c (also identified as
SPECULOOS-2 c), previously undetected by TESS. The orbital period of
this second planet was later confirmed by MuSCAT3 follow-up
observations.
We first inferred the properties of the host star by analyzing its
Lick/Kast optical and IRTF/SpeX near-infrared spectra, as well as its
broadband spectral energy distribution, and Gaia parallax. We then
derived the properties of the two planets by modelling multi-colour
transit photometry from TESS, SPECULOOS-South, MuSCAT3, ExTrA,
TRAPPIST-South, and SAINT-EX. Archival imaging, Gemini-South/Zorro
high-resolution imaging, and Subaru/IRD radial velocities also support
our planetary interpretation.
With a mass of 0.118±0.002M☉, a radius of
0.1556±0.0086R☉, and an effective temperature of 2850±75K,
LP 890-9 is the second-coolest star found to host planets, after
TRAPPIST-1. The inner planet has an orbital period of 2.73 d, a radius
of 1.320-0.027+0.053R⊕, and receives an incident stellar
flux of 4.09±0.12S⊕. The outer planet has a similar size of
1.367-0.039+0.055R⊕ and an orbital period of 8.46 d. With
an incident stellar flux of 0.906±0.026S⊕, it is located
within the conservative habitable zone, very close to its inner limit
(runaway greenhouse). Although the masses of the two planets remain to
be measured, we estimated their potential for atmospheric
characterisation via transmission spectroscopy using a mass-radius
relationship and found that, after the TRAPPIST-1 planets, LP 890-9 c
is the second-most favourable habitable-zone terrestrial planet known
so far (assuming for this comparison a similar atmosphere for all
planets).
The discovery of this remarkable system offers another rare
opportunity to study temperate terrestrial planets around our smallest
and coolest neighbours.
Description:
TESS PDCSAP photometry + ground-based follow-up transit photometry
obtained with SPECULOOS-South, TRAPPIST-South, ExTrA, MuSCAT3 and
SAINT-EX. Radial velocities obtained with Subaru/IRD.
Objects:
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RA (2000) DE Designation(s)
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04 16 31.16 -28 18 52.95 LP 890-9 = SPECULOOS-2 = TOI-4306 = TIC 44898913
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File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
sso.dat 174 5569 SPECULOOS-South photometry
ts.dat 160 65 TRAPPIST-South photometry
saintex.dat 144 45 SAINT-EX photometry
extra.dat 46 396 ExTrA photometry
muscat3.dat 61 2201 MuSCAT3 photometry
tess.dat 61 65777 TESS PDCSAP photometry
rv.dat 34 25 Subaru/IRD radial velocities
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Byte-by-byte Description of file: sso.dat
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Bytes Format Units Label Explanations
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1- 18 F18.10 d BJD Barycentric Julian date (TDB)
20- 37 F18.16 --- Flux Raw normalised flux
39- 59 F21.19 --- e_Flux Error on the raw normalised flux
61- 77 F17.14 pix Xshift Target position offset in x-direction
79- 95 F17.14 pix Yshift Target position offset in y-direction
97-114 F18.16 --- Airmass Airmass
116-133 F18.16 pix FWHM PSF FWHM
135-154 F20.14 e- Bck Background
156-160 F5.1 s Texp Exposure time
162-169 A8 --- Tel Telescope
171-172 A2 --- Filter [Iz riz] Filter
174 A1 --- Planet [bc] Planet
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Byte-by-byte Description of file: ts.dat
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Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 18 F18.10 d BJD Barycentric Julian date (TDB)
20- 37 F18.16 --- Flux Raw normalised flux
39- 59 F21.19 --- e_Flux Error on the raw normalised flux
61- 81 F21.18 pix Xshift Target position offset in x-direction
83-103 F21.18 pix Yshift Target position offset in y-direction
104-121 F18.16 pix FWHM PSF FWHM
123-140 F18.13 e- Bck Background
142-154 F13.11 --- Airmass Airmass
156-160 F5.1 s Texp Exposure time
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Byte-by-byte Description of file: saintex.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 18 F18.10 d BJD Barycentric Julian date (TDB)
20- 37 F18.16 --- Flux Raw normalised flux
39- 59 F21.19 --- e_Flux Error on the raw normalised flux
61- 81 F21.18 pix Xshift Target position offset in x-direction
83-102 F20.17 pix Yshift Target position offset in y-direction
104-112 F9.7 --- Airmass Airmass
114-131 F18.16 pix FWHM PSF FWHM
133-138 F6.1 e- Bck Background
140-144 F5.1 s Texp Exposure time
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Byte-by-byte Description of file: extra.dat
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Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 18 F18.10 d BJD Barycentric Julian date (TDB)
20- 31 F12.10 --- Flux Raw normalised flux
33- 39 F7.5 --- e_Flux Error on the raw normalised flux
41- 46 A6 --- Tel Telescope (ExTrA1 or ExTrA2)
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Byte-by-byte Description of file: muscat3.dat
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Bytes Format Units Label Explanations
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1- 14 F14.6 d BJD Barycentric Julian date (TDB)
16- 22 F7.5 --- Flux Raw normalised flux
24- 30 F7.5 --- e_Flux Error on the raw normalised flux
32- 37 F6.2 pix Xshift Target position offset in x-direction
39- 44 F6.2 pix Yshift Target position offset in y-direction
46- 51 F6.4 --- Airmass Airmass
53- 57 F5.2 pix FWHM PSF FWHM
59 A1 --- Filter [griz] Filter
61 A1 --- Planet [bc] Planet
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Byte-by-byte Description of file: tess.dat
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Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 18 F18.10 d BJD Barycentric Julian date (TDB)
20- 37 F18.16 --- Flux Raw normalised flux
39- 58 F20.18 --- e_Flux Error on the raw normalised flux
60- 61 I2 --- Sector TESS sector
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Byte-by-byte Description of file: rv.dat
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Bytes Format Units Label Explanations
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1- 14 F14.6 d BJD Barycentric Julian date (TDB)
16- 23 F8.6 km/s RV Radial velocity
25- 31 F7.5 km/s e_RV Error on the radial velocity
33- 34 A2 --- Band [YJ H] Bandpass
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Acknowledgements:
Laetitia Delrez, ldelrez(at)uliege.be
(End) Patricia Vannier [CDS] 29-Aug-2022